Pharmacological levels of LHRH agonist have antifertility effects in rats and women which appear to be mediated directly through the gonad; the mechanism of action is not clear at the present. This study is designed to measure LHRH receptors at not only the pituitary but also at the ovary during various hormonal states. D-Ser(TBU)6 LHRH-EA will be used as a radiologand and crude and purified membrane preparations evaluated for specific binding of the radioligand. Various species will be tested to determine species specificity for the LHRH receptor in the ovary and determine changes in LHRH receptor numbers and affinity in the pituitary and ovary at various times of reproduction and during exogenous hormone treatment. The LHRH receptor in the ovary may be involved in ovarian dysfunction of cystic ovaries. The ovaries from bovine and porcine species which are cystic will be compared with normal ovaries for changes in LHRH receptor numbers and affinity. These results may give more insight on using LHRH analogs as a nonsteroid contraceptive in women.